JP2006105229A - Selector valve and hydraulic driving unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a selector valve capable of preventing leakage between a bottom side and a rod side of the selector valve and a tank, and capable of improving pump performance. <P>SOLUTION: A pair of poppet valves (a valve seat tube 5c and a valve element 5d) are coaxially arranged so as to confront with each other, one of the poppet valves is operated to a closing direction, and thereby the other popett valve can be operated to an opening direction, and a waiting state maintaining means 5e is provided for always energizing the valve element 5d of the poppet valve to the closing direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention provides a switching valve that is interposed between a hydraulic pump that pumps working fluid in both forward and reverse directions and a tank that stores the working fluid, and that controls the flow of the working fluid in both forward and reverse directions. , These hydraulic pumps, tanks, hydraulic actuators operated by the hydraulic oil, an operation check valve that is interposed between the hydraulic actuators and the hydraulic pump and controls the forward / reverse bidirectional flow of the hydraulic oil therebetween The present invention relates to a hydraulic drive unit that independently supplies hydraulic power to a driven body.

  A hydraulic drive unit that easily provides hydraulic drive force as long as there is a power supply without using hydraulic piping is used, for example, for lifting and lowering work equipment with respect to the cultivated ground of special agricultural vehicles. The above application fields are expected and expanded.

  FIG. 9 is a hydraulic circuit diagram showing a basic configuration of the hydraulic drive unit.

  The hydraulic drive unit OU pumps the hydraulic oil in both forward and reverse directions by the forward / reverse rotating motor M in order to give the driven body W a hydraulic drive force independently while circulating the hydraulic oil in a closed system. A hydraulic pump OP, a hydraulic actuator OA (here, a hydraulic cylinder) that operates by the hydraulic oil and generates the driving force, a tank OT that stores hydraulic oil in a closed space, and between the hydraulic pump OP and the hydraulic actuator OA The operation check valve OC for controlling the forward / reverse bidirectional flow of the hydraulic oil and the switching valve OI for controlling the forward / reverse bidirectional hydraulic oil flow between the hydraulic pump OP and the tank OT are provided as basic components. Yes.

  The operating check valve OC basically pilots the hydraulic pressure to the check valve OCa to a pair of check valves OCa that allow only the flow of hydraulic oil from the hydraulic pump OP to the hydraulic actuator OA. And a pair of pilot lines OCb.

  The pair of check valves OCa includes a pipe line connecting one port of the hydraulic pump OP and the bottom side oil chamber OAa of the hydraulic actuator OA, the other port of the hydraulic pump OP and the rod side oil chamber OAb of the hydraulic actuator OA. And a pipe line connecting the two.

  The switching valve OI switches and connects between the tank OT and any pipe line between the hydraulic pump OP and the bottom side oil chamber OAa and the rod side oil chamber OAb of the hydraulic actuator OA.

  In the following description, the left side in the figure, such as the check valve OCa arranged in a pair of left and right, the one on the bottom side and the right side as the hydraulic oil entering and leaving the bottom side oil chamber OAa of the hydraulic actuator OA, The rod-side oil chamber OAb may be referred to as the rod side as it relates to the hydraulic oil entering and leaving the rod-side oil chamber OAb. Similarly, in the port of the hydraulic pump OP, the left side may be referred to as the bottom side and the right side may be referred to as the rod side.

  With such a configuration, according to the hydraulic drive unit OU, in a state where the hydraulic pump OP is stopped, the operation check valve OC allows any one of the bottom side oil chamber OAa and the rod side oil chamber OAb of the hydraulic actuator OA. The hydraulic oil is prevented from flowing out from the side, and the current stationary state of the hydraulic actuator OA is maintained against a predetermined external force.

  When the hydraulic pump OP rotates to discharge hydraulic oil to the bottom side port, the hydraulic oil is supplied from the hydraulic pump OP to the bottom side oil chamber OAa through the bottom side check valve OCa, and simultaneously piloted by the pilot line OCb. The rod side check valve OCa is pushed open by the hydraulic pressure of the bottom side check valve OCa, allowing the hydraulic oil to flow out from the rod side oil chamber OAb to the hydraulic pump OP, and between the hydraulic pump OP and the hydraulic actuator OA. A flow of hydraulic oil circulating in the clockwise direction is generated, and a driving force in the extending direction is generated in the hydraulic actuator OA.

  At this time, considering the case where the hydraulic actuator OA is a hydraulic cylinder as illustrated, the rod-side oil chamber OAb is compared to the amount of hydraulic oil flowing into the bottom-side oil chamber OAa with respect to the movement amount of the piston of the hydraulic cylinder. The amount of hydraulic fluid flowing out from the piston is reduced by the amount of the rod of the piston, but the switching valve OI is pushed by the relatively high pressure of the hydraulic fluid on the bottom side, and the switching valve OI is connected to the rod side oil chamber OAb and the tank OT. Are connected so that a shortage of hydraulic oil is supplied from the tank OT.

  On the other hand, when the hydraulic pump OP rotates so as to discharge the hydraulic oil to the rod side port, the reverse flow of the hydraulic oil occurs, and a driving force in the contracting direction is generated in the hydraulic actuator OA, and the bottom side oil is generated. The hydraulic fluid flowing into the hydraulic pump OP from the chamber OAa becomes redundant, but the excess hydraulic fluid is connected to the tank OT and the pipe line to the bottom side oil chamber OAa by the action of the switching valve OI opposite to the above. , It is returned to the tank OT.

  Note that the amount of hydraulic oil in the sealed tank OT increases or decreases depending on the position of the piston of the hydraulic cylinder that is the hydraulic actuator OA, and the gas pressure sealed in the tank OT varies. Therefore, the fluctuation of the gas pressure does not affect the operation of the hydraulic drive unit OU.

  Thus, the function of the hydraulic drive unit OU is exhibited and maintained while using the hydraulic actuator OA which is a closed system and has a difference in the amount of hydraulic oil entering and exiting due to its operation.

  The hydraulic drive unit OU includes the following additional elements in addition to the basic components described above.

  In the pipelines between the bottom side oil chamber OAa of the hydraulic actuator OA, the rod side oil chamber OAb and the respective check valves OCa of the operating check valve OC, hydraulic oil from the respective oil chambers OAa, OAb to the check valve OCa is provided. Slow return valves SR for restricting only the flow are provided respectively.

  The slow return valve SR is for preventing hunting that occurs when an external force is generated from the driven body W.

  From the pipelines between the slow return valves SR and the check valves OCa, pipelines provided with relief valves RV1 respectively branch to the tank OT. Similarly, from the pipe line between the hydraulic pump OP and the check valve OCa on the bottom side and the rod side, pipe lines each provided with a relief valve RV2 branch to the tank OT.

  These relief valves RV1 and RV2 allow excess hydraulic oil to escape to the tank OT when an abnormal pressure occurs in the branch source pipe.

  Furthermore, from the pipe line between the rod side and bottom side slow return valve SR and the check valve OCa, the pipe line provided with the emergency manual valve MV branches to the tank OT, and the hydraulic pump OP is powered. When the emergency manual valve MV is used, the hydraulic actuator OA can be manually operated by releasing the pipelines of the bottom side oil chamber OAa and the rod side oil chamber OAb of the hydraulic actuator OA to the tank OT. I am doing so.

  With such a configuration, this hydraulic drive unit OU achieves its basic functions well, and even if an abnormal situation occurs, it does not lead to damage of the unit OU, thus ensuring safety and reliability. Accident avoidance is ensured.

  FIG. 10 is a configuration diagram conceptually showing an example of a conventional hydraulic drive unit that embodies the hydraulic drive unit OU.

  The hydraulic drive unit 70 includes a hydraulic pump OP, a hydraulic actuator OA, a tank OT, an operation check valve OC, a switching valve O, a slow return valve SR, and a relief valve RV1 that constitute the hydraulic drive unit OU conceptually described with reference to FIG. , A hydraulic pump 61 having the same basic functions as RV2 and a mutual relationship, a hydraulic cylinder 62 as a hydraulic actuator, a tank 63, an operation check valve 64, a switching valve 65, a slow return valve 66, and relief valves 67 and 68. ing.

  In addition, the code | symbol 62a of the hydraulic cylinder 62 is a bottom side oil chamber, and the code | symbol 62b is a rod side oil chamber. Here, although the emergency manual valve MV shown in the hydraulic circuit diagram of FIG. 9 is not shown here, it is assumed that it is provided as necessary and is not shown, but the hydraulic pump OP It is assumed that an electric motor for driving is provided.

  Here, more specific configurations of the operation check valve 64 and the switching valve 65 will be described.

  The operated check valve 64 includes a valve accommodating portion 64a, a pilot portion 64i accommodated in the central portion of the valve accommodating portion 64a, and a pair of check valves 64b accommodated so as to face each other with the pilot portion 64i interposed therebetween. I have.

  The valve housing portion 64a includes a tubular housing tube 64aa and a housing tube lid 64ab that closes both ends of the housing in an oil-tight manner. A pilot portion 64i and a pair of check valves are provided in the internal housing space of the housing tube 64aa. 64b is stored in an oil-tight manner.

  The pilot portion 64i includes a cylindrical spool cylinder 64j that is accommodated in the center of the internal accommodation space of the accommodation cylinder 64aa without a gap, and a pilot spool 64l that is slidably accommodated in the internal cylindrical space of the spool cylinder 64j. Yes.

  The spool cylinder 64j is connected to pipes to the two ports of the hydraulic pump 61 at the cylinder part, and is also connected to pipes to the two openings 65b of the switching valve 65. Four openings 64k are provided to allow hydraulic fluid to flow between the hydraulic pump 61 and the switching valve 65.

  The spool 64l has a structure in which small-diameter pilot protrusions 64lb are provided at both ends of a cylindrical body 64la whose outer diameter is slidable on the inner periphery of the spool cylinder 64j. The spool cylinder 64j is partitioned into spools 64l, and two oil chambers communicating with the respective openings 64k are formed.

  With such a configuration, when the hydraulic pump 61 rotates while the pilot spool 64l always allows the hydraulic oil to flow between the hydraulic pump 61 and the tank 63, the hydraulic pressure of the oil chamber connected to the discharge side is changed. Since it becomes higher, it moves to the non-ejection side.

  The pair of check valves 64b are configured identically to each other, and include a valve seat body 64c, a valve body 64d that slides within the valve seat body 64c, and a spring 64h that normally biases the valve body 64d in the closing direction. And.

  The valve seat body 64c is a cylindrical body having a valve seat hole 64cb, one of which is a smaller opening, and a rod-side oil chamber 62b (opposite side) of the hydraulic cylinder 62 is formed in a cylinder portion near the valve seat hole 64cb side. Then, an opening 64ca is provided that enables the flow of hydraulic oil to and from the pipe line to the bottom side oil chamber 62a).

  The valve body 64d is a cylindrical body whose front end is closed as a conical valve portion 64e and which is the other opening. The spring 64h is accommodated in the inner cylinder portion 64f, and the rear end of the spring 64h and the valve seat The rear end of the body 64c is regulated by the housing cylinder lid 64ab of the valve housing portion 64a.

  An opening 64g is provided behind the end of the valve portion 64e of the valve body 64d to allow the hydraulic oil flowing from the opening 64ca to flow also to the inner cylinder portion 64f.

  The switching valve 65 includes a valve accommodating portion 65h, a cylindrical spool cylinder 65a that is accommodated in the valve accommodating section 65h without a gap, and a spool 65d that is slidably accommodated in the internal column space of the spool cylinder 65a. I have.

  The valve accommodating portion 65h is composed of a cylindrical accommodating cylinder 65ha and an accommodating cylinder lid 65hb that closes both end openings in an oil-tight manner, and the spool cylinder 65a is oil-tightly accommodated in the internal accommodation space of the accommodating cylinder 65ha. Has been.

  The spool cylinder 65a is connected to two pipe lines from the operation check valve 64 at the cylinder part, and two openings 65b for allowing the hydraulic oil to flow between these pipe lines, An opening 65c that allows the hydraulic oil to flow to the tank 63 to the tank 63 is provided at a position that does not interfere with the two openings 65b and that is the center of the spool cylinder 65a of both the openings 65b in the cylinder axis direction. Yes.

  The spool 65d has a shape in which two disks are skewered with a cylindrical body having an outer diameter smaller than the outer diameter of the disk, and the outer diameter of the disk portion 65f is smaller than the inner circumference of the spool cylinder 65a. The outer diameter is slidable.

  As shown in the drawing, the distance between the two disk portions 65f is the operation between the opening 65b on the operation check valve 64 side and the opening 65c on the tank 63 side when the spool 65d is located at the center. The oil distribution is blocked. In addition, when the spool 65d slides in one direction, for example, to the bottom side, the flow of hydraulic oil is permitted only through the bottom side of the opening 65b on the operation check valve 64 side and the opening 65c on the tank 63 side. It is supposed to be.

  The outer diameter of the middle shaft portion 65g sandwiched between the two circular disk portions 65f of the cylindrical body is thicker than the degree of maintaining the structural strength of the entire spool 65d, and operates between its outer periphery and the inner periphery of the spool cylinder 65a. It is thinner than the oil can circulate without resistance.

  The protruding length of the outer shaft portion 65e extending to the outside of the disc portion 65f is such that when the tip of the outer shaft portion 65e comes into contact with, for example, the bottom-side storage cylinder lid 65hb of the valve storage portion 65h, The flow of the hydraulic oil between only the bottom side of the opening 65b and the opening 65c to the tank 63 side is maintained.

  The respective parts constituting the spool 65d are fixed to each other, and the whole slides integrally.

  With such a configuration, the spool 65d has the above function of the disc portion 65f, and when the higher hydraulic fluid on the discharge side of the hydraulic pump 61 is supplied to one outer shaft portion 65e, the non-discharge side To connect the suction side of the hydraulic pump 61 and the tank 63. When the rotation of the hydraulic pump 61 is reversed and the discharge side and the suction side are reversed, the spool 65d operates in the reverse manner as described above.

  The operation of the operation check valve 64 and the switching valve 65 will be described.

  FIG. 10 itself shows a stationary body, that is, a state in which the hydraulic pump 61 is not rotating. In this state, no pressure is applied to the hydraulic oil from the hydraulic pump 61 side, and the hydraulic pump 61 and the operation check are performed. The hydraulic oil contained between the internal oil chambers of the valve 64 and the hydraulic oil contained between the oil chambers on both sides and the central side of the switching valve 65 and the tank 63 are stationary.

  The left and right check valves 64b of the operate check valve 64 are closed by the biasing force of the spring 64h, and the hydraulic oil from either the bottom side oil chamber 62a or the rod side oil chamber 62b of the hydraulic cylinder 62 is closed by the check valve 64b. Thus, the stationary state of the hydraulic cylinder 62 is maintained.

  Here, when the hydraulic pump 61 rotates to discharge hydraulic oil to the bottom side port, the hydraulic pressure opens the bottom side check valve 64b, and the hydraulic oil is supplied to the bottom side oil chamber 62a of the hydraulic cylinder 62. At the same time, the pilot spool 64l of the pilot part 64i is also moved to the right side of the figure by the oil pressure to the rod side, and the rod-side outer shaft part 64lb opens the rod-side check valve 64b. The hydraulic cylinder 62 is driven in the extending direction while allowing the hydraulic oil to flow from 62b.

  At the same time, the spool 65d of the switching valve 65 is also moved to the right side in the drawing by this hydraulic pressure to the rod side, and the hydraulic oil is allowed to flow between the rod side of the hydraulic pump 61 and the tank 63. In addition to the hydraulic oil from the rod side oil chamber 62b, the hydraulic oil from the tank 63 flows into the rod side port of the hydraulic pump 61, and the hydraulic oil in the rod side oil chamber 62b with respect to the bottom side oil chamber 62a of the hydraulic cylinder 62 Covers the shortage.

  On the other hand, when the hydraulic pump 61 rotates so as to discharge the hydraulic oil to the rod side port, the check valve 64 and the switching valve 65 are operated in reverse to drive the hydraulic cylinder 62 in the contracting direction. An excess of the hydraulic oil flow rate in the bottom side oil chamber 62a with respect to the oil chamber 62b is returned to the tank 63.

  In this way, the operation check valve 64 and the switching valve 65 perform their respective functions. Further, the pilot portion 64i of the operate check valve 64 serves as a pilot line OCb of the operate check valve OC provided in the hydraulic drive unit OU of FIG.

  However, in the hydraulic drive unit 70, the switching valve 65 is of a spool type, and the disk portion 65f of the spool 65d is slidable within the spool cylinder 65a. Therefore, in practice, a certain amount of hydraulic oil can be circulated between the pump 61, the operation check valve 64, and the tank 63 on the side closed by the switching valve 65. This is a cause of a decrease in pump efficiency.

  This problem is common not only as a component of a hydraulic drive unit but also in the case of a switching valve used in combination to control the flow of hydraulic oil in both forward and reverse directions.

Further, as other specific conventional examples of the hydraulic drive unit, there are those described in Patent Document 1 and Patent Document 2, but none of them solves the above problem.
Japanese Patent No. 2824659 (FIG. 1) Japanese Patent Laying-Open No. 2003-172307 (FIG. 1)

  SUMMARY OF THE INVENTION The present invention is intended to improve the above problem, and an object of the present invention is to provide a switching valve and a hydraulic drive unit that can prevent leakage between the bottom side and the rod side of the switching valve and between the tank and improve pump efficiency. .

The switching valve of the present invention is interposed between a hydraulic pump that pumps the working fluid in both forward and reverse directions and a tank that stores the working fluid, and controls the flow of the working fluid in both forward and reverse directions. A switching valve that
A pair of poppet valves are concentrically arranged opposite to each other, and one poppet valve is operated in the closing direction so that the other poppet valve can be operated in the opening direction. The poppet valve body is normally urged in the closing direction. A standby state maintaining means is provided. In addition, the hydraulic drive unit that independently gives the driven body hydraulic pressure exerts its function sufficiently.

  The hydraulic drive unit of the present invention is characterized by including a switching valve having the above characteristics.

  In the switching valve of the present invention, since the switching valve is made into a poppet, leakage between the bottom side of the switching valve, the rod side, and the tank can be prevented, and the pump efficiency can be improved. . In addition, since the hydraulic drive unit of the present invention includes this switching valve, the effect is exhibited as a unit.

  Embodiments (examples) of the present invention will be described below with reference to the drawings.

  FIG. 1 is a configuration diagram conceptually illustrating an example of a hydraulic drive unit including a switching valve according to the present invention.

  The hydraulic drive unit 10 is used for, for example, raising and lowering work equipment with respect to the cultivated ground of an agricultural special vehicle, which requires a simple and independent hydraulic drive force, and is also included in the hydraulic drive unit 10. In addition to being used as a component of the hydraulic drive unit 10, the switching valve 5 to be used is also used as a switching valve used in combination with an operating check valve for controlling the flow of hydraulic oil in both forward and reverse directions.

  The configuration includes a hydraulic pump 1 that includes an electric motor (not shown) and pumps hydraulic oil in both forward and reverse directions, and a hydraulic cylinder 2 that operates by the hydraulic oil and generates a driving force to the driven body W. A tank 3 that stores hydraulic oil in a closed space, an operation check valve 4 that controls the bidirectional flow of hydraulic oil between the hydraulic pump 1 and the hydraulic cylinder 2, and between the hydraulic pump 1 and the tank 3. It is characterized by comprising a switching valve 5 that controls the flow of hydraulic oil in both forward and reverse directions, and this switching valve 5 is a poppet type.

  The basic functions and interrelationships of these hydraulic pump 1, hydraulic cylinder 2, tank 3, operation check valve 4, and switching valve 5 are the hydraulic pump OP, hydraulic actuator OA, and tank constituting the conventional hydraulic drive unit OU. Since it is the same as OT, the operation check valve OC, and the switching valve OI, redundant description is omitted. In addition, the code | symbol 2a of the hydraulic cylinder 2 is a bottom side oil chamber, and the code | symbol 2b is a rod side oil chamber.

  Here, the slow return valve SR, the relief valves RV1, RV2, and the emergency manual valve MV shown in the hydraulic circuit diagram of FIG. 9 are not shown here, but these are provided as necessary. And

  The operated check valve 4 includes a valve accommodating portion 4a, a pilot portion 45i accommodated in a central portion of the valve accommodating portion 4a, and a pair of check valves 4b accommodated so as to face each other with the pilot portion 45i interposed therebetween. I have.

  In this example, the valve accommodating portion 4a includes a cylindrical accommodating cylinder 4aa and an accommodating cylinder lid 4ab that closes both end openings in an oil-tight manner.

  In order to make the explanation easy to understand, the valve accommodating portion 4a is shown as a cylindrical separate independent part. However, in an actual hydraulic drive unit, the structure body is a part of the structure of the entire unit. It is incorporated therein and includes an internal housing space for the valve housing portion 4a. When the operation check valve 4 is used as a single unit, it is desirable to use such a valve accommodating portion 4a.

  The pilot portion 45i and the pair of check valves 4b are oil-tightly accommodated in the internal accommodating space of the accommodating cylinder 4aa of the valve accommodating portion 4a.

  The pilot portion 45i includes a cylindrical spool cylinder 45j that is accommodated in the center of the internal accommodation space of the accommodation cylinder 4aa without a gap, and a pilot spool 45l that is slidably accommodated in the internal column space of the spool cylinder 45j. Yes.

  The spool cylinder 45j is connected to the pipes to the two ports of the hydraulic pump 1 and to the two openings 5cc of the switching valve 5, and these pipes, that is, Four openings 45k are provided that allow the hydraulic oil to flow between the hydraulic pump 1 and the switching valve 5.

  The spool 45l has a structure in which small-diameter pilot protrusions 45lb are provided at both ends of a cylindrical body 45la whose outer diameter is slidable on the inner periphery of the spool cylinder 45j. The spool cylinder 45j is partitioned by a spool 45l, and two oil chambers communicating with the respective openings 45k are formed.

  The pilot section 45i has the same configuration as the pilot section 64i built in the operation check valve 64 described in FIG. 10, and exhibits the same functions and effects.

  The pair of check valves 4b are configured identically to each other, and include a valve seat body 4c, a valve body 4d that slides within the valve seat body 4c, and a spring 4h that normally biases the valve body 4d in the closing direction. And.

  The valve seat body 4c is a tubular body having a valve seat hole 4cb, one of which is a smaller opening. Then, an opening 4ca is provided that allows the working oil to flow through the conduit to the bottom oil chamber 2a).

  The valve body 4d is a cylindrical body whose front end is closed as a conical valve portion 4e and which is the other opening. The spring 4h is accommodated in the inner cylinder portion 4f. The rear end of the spring 4h and the valve seat The housing cylinder lid 4ab of the valve housing portion 4a regulates the rear end of the body 4c.

  The valve seat hole 4cb of the valve seat body 4c is closed by the valve portion 4e of the valve body 4d biased by the spring 4h.

  An opening 4g is provided behind the end of the valve portion 4e of the valve body 4d to allow the hydraulic oil flowing from the opening 4ca to flow also to the inner cylinder portion 4f.

  The structure, function, and effect of the check valve 4b are the same as those of the check valve 64b built in the operate check valve 64 described with reference to FIG. This is the same configuration as the operation check valve 64 of FIG. 10, and exhibits the same functions and effects.

  The switching valve 5 has the same role as the switching valve 65 of FIG. 10 except that the structure of the valve is a poppet type.

  The structure is such that a pair of identical members are opposed to each other and are accommodated in the central portion in the valve accommodating portion 51. The valve seat cylinder 5c, the valve element 5d that slides in the valve seat cylinder 5c, and the valve element, respectively. There is provided a spring 5e for urging 5d toward each other.

  The valve accommodating part 51 is comprised from the accommodating cylinder 51a of a cylindrical body, and the accommodation cylinder cover 51b which closes the both-ends opening oil-tightly, and a pair of valve seat cylinder 5c is oil in the internal accommodation space of this accommodation cylinder 51a. Closely contained.

  In order to make the explanation easier to understand, the valve accommodating portion 51 is shown as a cylindrical separate independent part. However, in an actual hydraulic drive unit, the structure of the structural body is a part of the structural body of the entire unit. It is incorporated therein and includes an internal housing space of the valve housing portion 51 formed therein. When the switching valve 5 is used as a single unit, it is desirable to use such a valve accommodating part 51.

  The valve seat cylinder 5c is a cylindrical body having a stepped inner periphery, and the outer periphery thereof is fitted in the inner periphery of the housing cylinder 51a without any gaps and in an oil-tight manner. The inner peripheral side includes a small diameter portion 5ca and a large diameter portion 5cb, and the small diameter portion 5ca is connected to the small diameter portion 5ca of the valve seat cylinder 5c facing each other. The peripheral wall of the large diameter portion 5cb closest to the small diameter portion 5ca is provided with an opening 5cc that enables the flow of hydraulic oil to and from the pipe line to the hydraulic pump 1, and the peripheral wall of the small diameter portion 5ca is connected to the tank 3. An opening 5cd is provided that enables the flow of hydraulic oil to and from the pipeline.

  The valve body 5d has a shape in which a stepped protrusion is provided on one of the center sides of the disc, and the outer diameter of the disc portion 5da slides with respect to the inner periphery of the large diameter portion 5cb of the valve seat cylinder 5c. It is possible.

  The stepped protrusion is composed of a state-of-the-art small-diameter portion 5db, followed by a larger-diameter medium-diameter portion 5dc, followed by a valve gradient portion 5dd, and the intermediate-diameter portion 5dc is smaller than the small-diameter portion 5ca of the valve seat cylinder 5c. So that the valve gradient portion 5dd comes into contact with the step edge from the small diameter portion 5ca to the large diameter portion 5cb of the valve seat cylinder 5c to completely prevent the flow of hydraulic oil between the two. This is the reason why it is called a poppet type.

  The disk portion 5da is provided with a through hole 5de that allows the working oil to flow from the stepped protrusion side to the protrusionless side.

  The valve body 5d is incorporated in the valve seat cylinder 5c so that the tip of the small diameter portion 5db contacts the tip of the small diameter portion 5db of the opposing valve body 5d.

  The spring 5 e is inserted between the rear surface of the valve body 5 d and the housing cylinder lid 51 b of the valve housing portion 51.

  The switching valve 5 has a pair of poppet valves (a valve seat cylinder 5c and a valve body 5d) arranged coaxially opposite to each other so that the operation of one poppet valve in the closing direction allows the other poppet valve to operate in the opening direction. The function of the switching valve 5 having such a configuration will be described below.

  FIG. 1 itself shows a stationary body, that is, a state where the hydraulic pump 1 is not rotating. In this state, no pressure is applied to the hydraulic oil from the hydraulic pump 1 side, and the hydraulic pump 1 and the operation check are performed. The hydraulic oil contained between the internal oil chambers on both sides of the pilot portion 45 i of the valve 4 and the hydraulic oil contained between the internal oil chamber of the switching valve 5 and the tank 3 are stationary.

  The left and right check valves 4b of the operate check valve 4 are closed by the urging force of the spring 4h, and hydraulic oil from either the bottom side oil chamber 2a or the rod side oil chamber 2b of the hydraulic cylinder 2 is closed by the check valve 4b. Thus, the stationary state of the hydraulic cylinder 2 is maintained.

  Here, when the hydraulic pump 1 rotates so as to discharge hydraulic oil to the bottom side port, the hydraulic pressure opens the bottom side check valve 4b, and the hydraulic oil is supplied to the bottom side oil chamber 2a of the hydraulic cylinder 2, At the same time, the pilot spool 45l of the pilot portion 45i is also moved to the right side of the figure by this oil pressure, to the rod side, and the rod-side outer shaft portion 45lb opens the rod-side check valve 4b. The hydraulic oil flow from 2b is allowed, and a driving force in the extending direction is generated in the hydraulic cylinder 2.

  At the same time, the bottom side valve element 5d of the switching valve 5 moves to the right side in the figure, the rod side, the rod side valve element 5d moves to the rod side, and the oil on the stepped protrusion side of the bottom side valve element 5d. The chamber allows the hydraulic oil to flow with the tank 3 via the opening 5cd of the valve seat cylinder 5c, and the amount of hydraulic oil in the rod side oil chamber 2b relative to the bottom side oil chamber 2a of the hydraulic cylinder 2 is insufficient. Is supplied from the tank 3.

  On the other hand, when the hydraulic pump 1 rotates so as to discharge the hydraulic oil to the rod side port, the pair of check valves 4b, the pilot unit 45i, and the switching valve 5 of the operate check valve 4 operate in the reverse manner to the above. Driving force in the contracting direction is generated in the cylinder 2, and excess hydraulic oil at that time is allowed to flow through the tank 3 in the bottom side valve body 5 d and is returned to the tank 3.

  In any of the above-described driving cases, the closing between the valve body 5d of the switching valve 5 and the valve seat cylinder 5c is configured as a poppet type, so that the flow of hydraulic oil can be completely closed, and the spool as shown in FIG. Compared with the switching valve 65 of the type, leakage between the bottom side, the rod side, and the tank can be prevented, and the pump efficiency can be improved.

  Further, the predetermined gap between the outer diameter of the intermediate diameter portion 5dc of the valve body 5d of the switching valve 5 and the small diameter portion 5ca of the valve seat cylinder 5c appropriately limits the amount of hydraulic oil passing between the two. Thus, the oil pressure on the tank 3 side acts on the area of the medium diameter portion 5dc only on the stepped protrusion side, and among the forces acting on both surfaces of the disc portion 5da of the valve body 5d, it acts on the stepless side relatively. The switching force is increased so that the switching action is exhibited.

    Further, the spring 5e always urges the opposing valve body 5d in the center (opposite) direction, and both the valve bodies 5d have their middle diameter portions 5dc engaged with the small diameter portion 5ca of the valve seat cylinder 5c (not shown). State), a standby state maintaining means for maintaining the standby state in which the switching action can be exhibited.

  Such a standby state maintaining means is not limited to the spring of this example, but is one that generates an elastic biasing force and is resistant to hydraulic oil, such as oil-resistant rubber, oil-resistant elastic synthetic resin, etc. There may be.

  The switching valve 5 described in FIG. 1 exhibits the above functions and effects as components of the hydraulic drive unit 10 and is used in combination with an operation check valve to control the flow of hydraulic oil in both forward and reverse directions. The above-mentioned functions and effects are exhibited as a switching valve.

  Moreover, the hydraulic drive unit 10 provided with such a switching valve 5 exhibits these functions and effects as a unit.

  In the second to eighth embodiments described below, the switching valve described in the first embodiment is basically made into a poppet, and the switching valve is integrated into the operation check valve by an absorption integrated, fixed type or Various combinations of variable slow return absorption integration will be described.

  FIGS. 2A and 2B are configuration diagrams conceptually showing another example of the hydraulic drive unit provided with the switching valve of the present invention. Accordingly, the same parts as those already described are denoted by the same reference numerals and redundant description is omitted. In addition, in the case where there is a separate code for the aggregate of each part, only the code of the aggregate may be shown to avoid complication.

  The hydraulic drive unit 10A in FIG. 2A differs from the hydraulic drive unit 10 in FIG. 1 in that the operation check valve 4A accommodates a poppet type switching valve 5A and is integrated. Therefore, the check valve 4b is exactly the same as that accommodated in the operation check valve 4 of the hydraulic drive unit 10, and here, the different switching valve 5A will be described.

  The switching valve 5A is a valve seat cylinder 5h, a valve that slides in the valve seat cylinder 5h, respectively, with a pair of identical members facing each other and accommodated in the central portion of the accommodation cylinder 4aa of the operation check valve 4A. The body 5i is not included, which corresponds to the spring 5e required for the switching valve 5 of FIG.

  The valve seat cylinder 5h is a cylindrical body having a stepped inner peripheral side, and the outer periphery thereof is fitted in the inner periphery of the accommodating cylinder 4aa without any gap and in an oil-tight manner. The inner peripheral side is composed of a small diameter portion 5ha and a large diameter portion 5hb, and the small diameter portion 5ha is connected to the small diameter portion 5ha of the switching valve 5A facing the inner diameter side. An opening 5hc is provided in the peripheral wall of the large-diameter portion 5hb closest to the small-diameter portion 5ha. The opening 5hc enables the flow of hydraulic oil to and from the pipe line to the hydraulic pump 1. An opening 5hd is provided that allows the hydraulic oil to flow through the pipe.

  The valve body 5i has a shape in which one stepped projection is provided at one of the centers of both sides of the disc and the stepless projection is provided on the other. The outer diameter of the disc portion 5ia is the large diameter portion 5hb of the valve seat cylinder 5h. It is slidable with respect to the inner periphery.

  The stepped protrusion is composed of a state-of-the-art small-diameter portion 5ib, a larger-diameter medium-diameter portion 5ic following this, and a valve gradient portion 5id following this, and the medium-diameter portion 5ic is formed with respect to the small-diameter portion 5ha of the valve seat cylinder 5h. The valve gradient portion 5id comes into contact with the step edge from the small diameter portion 5ha to the large diameter portion 5hb of the valve seat cylinder 5h to prevent the flow of hydraulic oil between the two. This is the reason why it is called a poppet type.

  The disc portion 5ia is provided with a through hole 5ie that allows the working oil to flow from the stepped protrusion side to the stepless protrusion side.

  The stepless projection is called a rear projection 5if. When the valve body 5i moves to the maximum extent, the tip of the rear projection 5if fully opens the conical valve portion 4e of the valve body 4d constituting the check valve 4b. The inflow of hydraulic oil from the valve 4b is permitted.

  The valve body 5i is incorporated in the valve seat cylinder 5h so that the tip of the small diameter portion 5ib contacts the tip of the small diameter portion 5ib of the opposing switching valve 5A.

  Such a switching valve 5A substantially corresponds to the point accommodated in the operation check valve 4A, the point provided with the rear projection 5if, and the spring 5e, compared to the switching valve 5 of FIG. The difference is that things are omitted.

  As for the point accommodated in the operation check valve 4A, as a result of intensive studies by the inventors, the pilot portion 45i and the switching valve 5 in the operation check valve 4 in FIG. This is the result of finding out that if the shape of the switching valve is devised, it can be integrated into the pilot section. As will be described below, the pilot function and the switching function are exhibited simultaneously in such a configuration. Is.

  The rear projection 5if is for entering the valve seat hole 4cb of the check valve 4b and pushing the valve portion 4e, and is provided in relation to the opposing parts. Therefore, as will be described in the next example, it can be made unnecessary by the structure of the check valve.

  The spring 5e is replaced by a spring 4h provided in the check valve 4b.

  The operation check valve 4A operates as follows, and exhibits the same functions and effects as the operation check valve 4 and the switching valve 5 in FIG.

  First, the state shown in this figure is a stationary state of the pump 1. At this time, the switching valve 5A is in a neutral state as shown, the pair of check valves 4b are also kept closed, and the stationary state of the hydraulic actuator 2 is kept.

  Here, when the hydraulic pump 1 rotates so as to discharge the hydraulic oil to the bottom side port, the high-pressure hydraulic oil passes through the opening 5hc of the bottom valve seat cylinder 5h and the through hole 5ie of the valve body 5i. The oil flows into the oil chamber between the valve body 5i and the check valve 4b, whereby the bottom-side check valve 4b is opened, and hydraulic oil is supplied to the bottom-side oil chamber 2a of the hydraulic cylinder 2.

  At the same time, the valve body 5i of the bottom side switching valve 5A moves to the right side of the figure, the rod side, and the valve body 5i of the rod side switching valve 5A moves to the right side of the figure, whereby the check valve on the rod side 4b is opened, and hydraulic oil from the rod side oil chamber 2b of the hydraulic cylinder 2 passes through the check valve 4b, the through hole 5ie provided in the valve body 5i of the rod side switching valve 5A, and the opening 5hc of the valve seat cylinder 5h. Then, it flows into the hydraulic pump 1 and causes the hydraulic cylinder 2 to generate a driving force in the extending direction.

  At this time, in the rod side switching valve 5A, the oil chamber on the stepped projection side of the valve body 5i can flow the hydraulic oil to the tank 3 through the opening 5hd of the valve seat cylinder 5h. The shortage of the hydraulic oil amount in the rod side oil chamber 2b relative to the two bottom side oil chambers 2a is supplied from the tank 3.

  On the other hand, when the hydraulic pump 1 rotates to discharge hydraulic oil to the rod side port, the pair of check valves 4b of the operation check valve 4A and the switching valve 5A operate in the reverse manner to the above and contract into the hydraulic cylinder 2. A driving force in the direction is generated, and excess hydraulic oil at that time is allowed to flow through the tank 3 at the bottom side switching valve 5 </ b> A and is returned to the tank 3.

  In this way, this operation check valve 4A is an integral integration of a poppet type switching valve, and in this way, in addition to the effect of poppeting, the operation check valve can be multi-functional and a space for providing a separate switching valve. Cost, a pipe line connecting the switching valve and the check valve, etc. are not required. Further, the hydraulic drive unit 10A provided with such an operation check valve 4A can reduce the size and cost of the apparatus while maintaining its function.

  The hydraulic drive unit 10A ′ shown in FIG. 2B is in contact with the check valve 4b ′ and the switching valve 5A ′ in the operating check valve 4A ′ as compared with the hydraulic drive unit 10A shown in FIG. The difference is that the protrusion for realizing the above is on the check valve side.

  In the hydraulic drive unit 10A in FIG. 2A, the check valve 4b is the same as the check valve 4b in the hydraulic drive unit 10 in FIG. 1, but in this example, the check valve 4b ′ and the switching valve 5A ′ are the same. Are provided on the check valve 4b 'side, that is, the conical valve portion 4e' of the valve body 4d 'constituting the check valve 4b' is provided at the tip, A protrusion 4ea is provided to replace the rear protrusion 5i of the valve body 5i constituting the switching valve 5A of the hydraulic drive unit 10A.

  Correspondingly, there is nothing corresponding to the rear protrusion 5i in the disc part 5ia of the valve body 5i 'constituting the switching valve 5A'.

  Even with such a configuration, it is obvious that the same function and effect as the hydraulic drive unit 10A of FIG.

  While the second embodiment is based on the effect of popping the switching valve, the operation check valves 4A and 4A 'described with reference to FIGS. 2A and 2B are hydraulic drive units 10A and 10A, respectively. The above-mentioned function and effect are exhibited as a part of ′, and the function and effect are also exhibited as an operation check valve having a switching valve function used for controlling the flow of hydraulic oil in both forward and reverse directions.

  Further, the hydraulic drive units 10A and 10A ′ provided with such operation check valves 4A and 4A ′ exhibit these functions and effects as a unit.

  Note that the operation check valves 4A and 4A 'in this example are characterized in that the switching valve is integrated and popped as compared to the conventional example.

  Further, the idea of absorbing and integrating the switching valve described here into the operation check valve is based on the result of the inventor's diligent study. As a result, the pilot portion 45i and the switching valve 5 in the operation check valve 4 in FIG. This is the result of finding that the same operation is performed from the point of backflow control, and that it can be integrated into the pilot section if the shape of the switching valve is devised.

  FIG. 3A is a block diagram conceptually showing another example of a hydraulic drive unit provided with the switching valve of the present invention, FIG. 3B is a detailed view of a valve portion of the check valve of FIG. It is AA arrow sectional drawing of b).

  This hydraulic drive unit 10B is different from the hydraulic drive unit 10A ′ in FIG. 2B in that the pair of check valves 4i housed in the operation check valve 4B also has a fixed slow return valve function. Yes.

  Compared to the check valve 4b 'shown in FIG. 2 (b), the check valve 4i has a common valve seat body 4c, but the valve body 4j has one step at the tip side of the conical valve portion 4k. The difference is that it is a protrusion.

  The tip protrusion 4ka of the stepped protrusion is pushed by the hydraulic oil discharged from the hydraulic pump 1, and the valve body 4j becomes the rear end (the state where the rear end of the valve body 4j abuts against the housing lid 4ab). At this time, the valve seat hole 4cb is located and the valve 4i is fully opened.

  The step 4kb following the tip protrusion 4ka has an outer diameter that is slidable with respect to the inner diameter of the valve seat hole 4cb and prevents the flow of hydraulic oil. The width of the step 4kb is that of the check valve 4i. The valve seat hole 4cb is fully opened until it is opened by the pilot action of the switching valve 5A '(the valve gradient portion 5id of the valve body 5i of the discharge side switching valve 5A' closes the small diameter portion 5ha of the valve seat cylinder 5h). On the other hand, the flow of hydraulic oil other than that by the fixed throttle passage 4kc described below is blocked.

  The stepped portion 4 kb is provided with a fixed throttle passage 4 kc having a fixed depth from the outer periphery from the front end to a position where the conical gradient is reached, and while the check valve 4 i is opened by the pilot action, the hydraulic oil having a predetermined flow rate is provided. The reverse flow is permitted.

  The fixed throttle passage 4kc is incorporated in the check valve 4i, and as a whole, when FIG. 3 and FIG. 9 are compared, inflow of hydraulic oil from the hydraulic pump 1 to the hydraulic cylinder 2 is permitted. When the valve 4i opens by a pilot action to open a predetermined opening and allows the backflow of the hydraulic oil from the hydraulic cylinder 2 to the hydraulic pump 1, the hydraulic oil from the hydraulic cylinder 2 to the hydraulic pump 1 is discharged by this throttle passage 4kc. The flow is permitted, and the role of the slow return valve SR of FIG. 9 can also be achieved.

  In addition to the fixed throttle passage 4kc as described above, the check valve is provided with a fixed throttle, and the outer diameter of the step portion is set to the inner diameter of the valve seat hole 4cb of the check valve 4b so as to correspond to the passage area. It is also possible to make it smaller.

  In this way, the third embodiment is based on the effect of popping the switching valve, and conventionally, only a small additional process of providing such a fixed throttle passage 4kc on the check valve 4i has been conventionally performed separately. The fixed slow return valve provided can be dispensed with.

  Such a fixed throttle passage 4kc is a check that is commonly used for the operation check valve 4 constituting the hydraulic drive unit 10 of FIG. 1 and the operation check valve 4A constituting the hydraulic drive unit 10A of FIG. 2A. The valve 4b can be additionally provided, and the same effect is exhibited.

  Further, the operation check valve 10B of this example is characterized in that a switching valve is integrated and popped, and a fixed slow return valve is also integrated, as compared with the conventional example.

  FIG. 4A is a configuration diagram conceptually showing another example of the hydraulic drive unit provided with the operate check valve of the present invention, and FIG. 4B is a detailed view of the valve portion of the check valve of FIG.

  Compared with the hydraulic drive unit 10B of FIG. 3, this hydraulic drive unit 10C is common in that the pair of check valves 4l accommodated in the operation check valve 4C also has a slow return function. The check valve 4l is different in that the slow return function of the valve 4i is a variable type that can change the throttle amount of the slow return, compared to the fixed type that cannot change the throttle amount. .

  Compared with the check valve 4i of FIG. 3, the check valve 4l is configured such that the valve seat body 4m is accommodated so as to be adjustable in and out of the valve accommodating portion 4a ', and the throttle portion 4oa of the valve portion 4o of the valve body 4n. Is different.

  The switching valve 5 side portion of the valve seat body 4m is common to the toilet seat body 4c of the check valve 4i of FIG.

  On the counter-switching valve 5 side portion of the valve seat body 4m, a disc 4ma for restricting the rear end of the spring 4h on the inner periphery, a stop ring 4mb for positioning the disc 4ma, and a rear opening of the valve seat body 4m are oiled. A lid 4mc that closes tightly is provided, and a male screw 4md is formed on the outer periphery. A locking nut 4me is externally fitted to the male screw 4md.

  The valve accommodating portion 4a 'does not have an accommodating cylinder lid 4ab as compared with the valve accommodating portion 4a of FIG. 1, and instead, a female screw 4ac corresponding to the male screw 4md of the valve seat body 4m is provided inside the opening at both ends of the accommodating cylinder 4aa'. The difference is that it is formed.

  As a result, the male screw 4md of the valve seat body 4m can be screw-fitted to the female screw 4ac of the valve accommodating portion 4a ′, and the fitting state at an arbitrary position can be fixed with the lock nut 4me.

  The throttle gradient portion 4oa of the valve portion 4o is gentler than the conical gradient for closing the valve portion 4o. The protrusion 4ob at the tip is the same as the protrusion 4ea provided on the valve portion 4e 'of the valve body 4d constituting the check valve 4b' in FIG.

  According to the operation check valve 4C provided with this check valve 4l in such a configuration, not only exhibits a slow return function, but also adjusts the insertion / extraction position of the valve seat body 4m containing the valve body 4n, It is possible to adjust at which portion of the throttle gradient portion 4oa of the valve portion 4o the slow return throttle is exerted, and a variable throttle can be obtained.

  In addition, by making the gradient of the aperture gradient portion 4oa gentle, it is possible to adjust the variable aperture more finely. The variable throttle can be realized by a gradient portion that changes the radius as in this example, but it can also be a variable throttle passage that changes the cross-sectional area of the throttle passage provided in the stepped portion 4 kb of FIG. Good.

  The operation check valve 10C of this example is characterized in that the switching valve is integrated and popped, and further, a variable type slow return valve is also integrated as compared with the conventional example.

  In the second embodiment to the fourth embodiment, the operation check valve in which the poppet type switching valve of the present invention is absorbed and integrated has been described, but the function as described in the first embodiment is also adopted as the switching valve absorbed in this. The effect is exhibited in any case, and the function and effect when combined are shared.

  FIG. 5 (a) is a block diagram conceptually showing another example of a hydraulic drive unit provided with the switching valve of the present invention, (b) is a detailed view of the main part of (a), and (c) is a schematic diagram of (b). It is BB arrow partial view.

  The hydraulic drive unit 10D shown in FIG. 5 is different from the hydraulic drive unit 10 shown in FIG. 1 in that the operation check valve 4D is an integral integral of a fixed slow return valve.

  Specifically, compared to the hydraulic drive unit 10 of FIG. 1, the check valve 4i housed in the operation check valve 4D is different from the check valve 4i of the operation check valve 4B in which the fixed slow return valve of FIG. On the other hand, the pilot portion 45m is correspondingly different from the pilot portion 45i accommodated in the operation check valve 4 of FIG.

  The pilot portion 45m includes a spool cylinder 45n, a pilot spool 45p, and a movement restricting means 45o. The spool cylinder 45n includes the opening 45k except that the movement restricting means 45o is provided. It is common with the spool cylinder 45j of 45i.

  The pilot spool 45p is shorter than the pilot spool 45l of the pilot portion 45i in FIG. 1 by the length of the pilot protrusion 45pb by the amount of protrusion of the tip protrusion 4ka of the valve body 4j of the check valve 4i. Is different.

  The movement restricting means 45o determines the amount of pilot movement of the pilot spool 45p, that is, the amount of movement when moving to the non-discharge side when pushed by the hydraulic oil discharged from the pump 1, This restricts the range of 4 kc to function, thereby exhibiting a slow return throttling function.

  Thus, according to the hydraulic drive unit 10D, the switching valve 5 also exhibits the effect that the fixed slow return valve is integrated with the operation check valve 4D while exhibiting the poppet function and effect.

  FIG. 6A is a block diagram conceptually showing another example of the hydraulic drive unit provided with the switching valve of the present invention, FIG. 6B is a detailed view of the main part of the spool of FIG. 6A, and FIG. FIG.

  The hydraulic drive unit 10E shown in FIG. 6 is similar to the hydraulic drive unit 10D shown in FIG. 5 in that the operation check valve 4E is an integral integral of a fixed slow return valve. Compared with the operation check valve 4D, the fixed throttle for the slow return valve is provided on the check valve 4i side, whereas in this operation check valve 4E, the fixed throttle for the slow return valve is provided on the pilot portion 45q side. Is different.

  Specifically, compared to the hydraulic drive unit 10D of FIG. 5, the check valve 4b accommodated in the operate check valve 4E is the same as the check valve 4b of the operate check valve 4 of FIG. Correspondingly, the pilot part 45m accommodated in the operation check valve 4D of FIG. 5 is partially different.

  The pilot portion 45q includes a spool cylinder 45j and a pilot spool 45r, and the spool cylinder 45j is common to the spool cylinder 45j of the pilot portion 45i of FIG.

  The pilot spool 45r has the same cylindrical body 45ra as the pilot spool 45l of the pilot portion 45i of FIG. 1, but the pilot protrusion 45rb provided with the fixed throttle passage 5gc is different.

  The pilot protrusion 45rb is slidable with respect to the inner diameter of the valve seat hole 4cb of the check valve 4b so as to prevent the flow of hydraulic oil. The length of the protrusion 45rb is such that the pilot function is exerted, that is, the spool 45r is pushed and moved by the hydraulic oil discharged from the pump 1, and the check valve 4b on the counter discharge side is moved to a predetermined pilot opening degree. It is only open.

  The fixed throttle passage 45rc is provided on the outer periphery of the pilot protrusion 45rb, and the space cross-sectional area of the groove does not change in the axial direction of the pilot spool 45r.

  Even in such a configuration, when the check valve 4b is pilot-opened, the flow rate of the hydraulic oil is reduced only by the fixed throttle passage 45rc, and the function of a so-called fixed type slow return valve is exhibited. .

  In addition to the fixed throttle passage 45rc as described above, the pilot spool is provided with the fixed throttle passage 45rc as described above, and the pilot projection has an outer diameter that corresponds to the inner diameter of the valve seat hole 4cb of the check valve 4b. It is also possible to make it smaller.

  Further, when the fixed throttle is provided on the pilot portion side as described above, it is not necessary to provide the movement restricting means 45o that was necessary in the case of FIG. This is because the fixed aperture provided here can be installed so that it always operates while its pilot function is being demonstrated.

  On the other hand, in the case of FIG. 5, the fixed throttle is provided on the check valve 4 i side, and the check valve 4 i needs to be fully opened by the hydraulic oil discharged from the hydraulic pump 1. A tip projection 4ka corresponding to full opening and a stepped portion 4kb provided with a throttle passage 4kc corresponding to pilot opening are continuously provided at the tip of each.

  Therefore, since the pilot spool needs to open the valve body 4j of the check valve 4i within the effective range of the throttle passage 4kc corresponding to the pilot opening, the movement restricting means 45o is required.

  Thus, according to the hydraulic drive unit 10E, the switching valve 5 also exhibits the effect that the fixed slow return valve is integrated with the operation check valve 4E while exhibiting the poppet function and effect.

  FIG. 7 is a block diagram conceptually showing another example of the hydraulic drive unit provided with the switching valve of the present invention.

  The hydraulic drive unit 10F shown in FIG. 7 is different from the hydraulic drive unit 10 shown in FIG. 1 in that the operation check valve 4F is an integral integration of a variable slow return valve. In other words, the fixed slow return valve built in the operation check valve 4D of FIG. 5 is variable.

  Specifically, compared to the hydraulic drive unit 10 of FIG. 1, the check valve 4l accommodated in the operation check valve 4F is different from the check valve 4l of the operation check valve 4C in which the variable slow return valve of FIG. On the other hand, the pilot part 45m is the same as the pilot part 45m accommodated in the operation check valve 4D that absorbs and integrates the fixed slow return valve of FIG.

  In this way, according to the hydraulic drive unit 10F, the switching valve 5 exhibits the effect that the variable slow return valve is integrated with the operation check valve 4F while exhibiting the poppet function and effect.

  FIG. 8A is a block diagram conceptually showing another example of the hydraulic drive unit provided with the switching valve of the present invention, and FIG. 8B is a detailed view of the main part of the spool in FIG.

  The hydraulic drive unit 10G shown in FIG. 8 is similar to the hydraulic drive unit 10F shown in FIG. 7 in that the operation check valve 4G is integrated with a variable type slow return valve. The difference is that the change aperture is provided on the pilot portion 45s side. In other words, the fixed slow return valve built in the operation check valve 4E of FIG. 6 is made variable.

  Specifically, as compared with the hydraulic drive unit 10F of FIG. 7, the check valve 4p accommodated in the operation check valve 4G can be inserted into and removed from the valve accommodating portion 4a ′, the valve seat body 4m, the valve body 4d, and the spring 4h. On the other hand, the pilot part 45 s is provided with a variable stop as compared with the pilot part 45 m of FIG. 7.

  The valve seat body 4m of the check valve 4p is in common with the valve seat body 4m used for the check valve 4b of the operating check valve 4C in which the variable slow return valve of FIG. 4 is absorbed and integrated. On the other hand, the valve body 4d of the check valve 4p is common to the valve body 4d of the check valve 4b of FIG.

  The pilot portion 45s includes a spool cylinder 45n, a pilot spool 45t, and a movement restricting means 45o. The spool cylinder 45n and the movement restricting means 45o include a spool cylinder 45n that constitutes the pilot portion 45m of FIG. Common to the restricting means 45o.

  The pilot spool 45t includes a cylindrical body 45ta and a pilot protrusion 45tb provided with a variable throttle passage 45tc. The shape of the cylindrical body 45ta, the outer diameter and the length of the pilot protrusion 45tb are fixed throttles constituting the pilot portion 45g of FIG. The pilot spool 45r is provided with the cylindrical body 45ra and the pilot protrusion 45rb.

  The difference is that, as shown in FIG. 8B, the variable throttle passage 45tc provided in the pilot projection 45tb is a variable throttle whose cross-sectional area of the groove space changes with respect to the axial direction of the pilot spool 45t. That is.

  If the degree of change of the variable aperture is moderated, the aperture can be adjusted more finely. Further, as in this example, the sectional area of the throttle passage may be changed, but the radius of the tip portion of the pilot protrusion 45tb is changed as in the throttle gradient portion 4oa of FIG. 4B. May be.

  In the case of this variable type slow return valve, the movement restricting means is required even when the variable throttle is provided on the pilot part side and the switching valve side. This is because it is meaningless that the check valve can be taken in and out unless the pilot operating range of the pilot unit and the switching valve that are opposed to the check valve is regulated within a certain range.

  Thus, according to this hydraulic drive unit 10G, the switching valve 5 exhibits the effect of integrating the fixed slow return valve with the operation check valve 4G while exhibiting its poppet function and effect.

  In the first to eighth embodiments, the switching valve is basically made into a poppet, and the switching valve is integrated into the operation check valve, and the fixed or variable slow return valve is fixed to the operation check valve. Although various combinations such as absorption integration have been described, these combinations are not limited to those exemplified here, and other combinations are possible, and in that case, a synergistic effect of the combination is exhibited.

  In the first to eighth embodiments, the function and effect of the switching valve and the operation check valve have been described. However, the effect of these switching valve and the operation check valve is not limited to a single unit. The hydraulic drive unit having a valve is also exhibited as a unit.

  The switching valve of the present invention is interposed between a hydraulic pump that pumps the working fluid in both forward and reverse directions and a tank that stores the working fluid, and controls the flow of the working fluid in both forward and reverse directions. Therefore, it can be used in all industrial fields where high efficiency is required by preventing leakage of unnecessary hydraulic oil between the pump and tank.

  Further, the hydraulic drive unit of the present invention can be used in any industrial field in which a driven force is independently applied to a driven body and high efficiency is required.

The block diagram which shows notionally an example of the hydraulic drive unit provided with the switching valve of this invention (A), (b) is a block diagram which shows notionally other examples of the hydraulic drive unit provided with the switching valve of this invention. (A) is a block diagram which shows notionally the other example of the hydraulic drive unit provided with the switching valve of this invention, (b) is a valve part detailed drawing of the check valve of (a), (c) is (b). AA arrow cross-sectional view (A) is a block diagram which shows notionally other examples of the hydraulic drive unit provided with the switching valve of this invention, (b) is a valve part detailed drawing of the check valve of (a). (A) is a block diagram which shows notionally other examples of the hydraulic drive unit provided with the switching valve of this invention, (b) is a principal part detailed drawing of (a), (c) is BB arrow of (b). Partial view (A) is a block diagram which shows notionally other examples of the hydraulic drive unit provided with the switching valve of this invention, (b) is a spool principal part detail drawing of (a). The block diagram which shows notionally other examples of the hydraulic drive unit provided with the switching valve of this invention (A) is a block diagram which shows notionally other examples of the hydraulic drive unit provided with the switching valve of this invention, (b) is a spool principal part detail drawing of (a). Hydraulic circuit diagram showing the basic configuration of the hydraulic drive unit The block diagram which shows notionally an example of the hydraulic drive unit provided with the conventional operation check valve

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hydraulic pump 2 Hydraulic actuator 3 Tank 4-4G Operate check valve 4a, 4a 'Valve accommodating part 4b, 4i, 4l, 4p Check valve 5-5A Switching valve 5e Standby state maintenance means (spring)
10-10G hydraulic drive unit

Claims (4)

A switching valve that is interposed between a hydraulic pump that pumps the working fluid in both forward and reverse directions and a tank that stores the working fluid, and that controls the flow of the working fluid in both forward and reverse directions;
A pair of poppet valves are concentrically arranged opposite to each other, and one poppet valve is operated in the closing direction so that the other poppet valve can be operated in the opening direction. The poppet valve body is normally urged in the closing direction. A switching valve, characterized in that a standby state maintaining means is provided.   The switching valve according to claim 1, wherein the standby state maintaining means is a spring.   It is used in a hydraulic drive unit that independently applies a hydraulic drive force to a driven body, and is interposed between a hydraulic pump that pumps the working fluid in both forward and reverse directions and a tank that stores the working fluid. The switching valve according to claim 1 or 2.   A hydraulic drive unit comprising the switching valve according to claim 3.

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